You've been doing a lot of fiddling with the machinery as part of finding the extruder problem, so: did you, at any time, even once, unplug / disconnect the Z axis motor when the power was turned on?

If so, that likely killed a driver transistor in that channel. Order a new RAMBo board along with the new motor.

No I have not disconnected the motor while power was ever turned on. In addition to that, this problem appeared before I ever took anything apart and I bought the machine completely assembled. It has been working fine for 2.5 years, never touched the motor at all until this problem happened a few days ago now.

It looks like i'll just bite the bullet and order a new board and motor. I still would like to investigate the actual failure point however. Do I have to call Makergear directly to order a new Z motor? I dont see it for sale on their site.

I went ahead and said fuck it and just completely look apart the motor since I planned on replacing it anyway so I can see if there is some obvious failure and I have never taken apart a stepper before. After looking inside if it and seeing how it's made, it looked so simple I would be astonished if this thing actually failed short if literally the inductor wire frying. I cleaned up the inside, put everything back together and the motor still seemed to worked the same.

Now I took a closer look at the Rambo board as now that is really suspect, and on closer examination it looked like the stepper motor drives for each axis is identical. I went ahead and connected the Z motor to the X and Y drive. It seemed to work perfect other than turning slower. It never stalled and it always turned in the correct direction. Connected it back to the Z driver and the problems were back. I then connected the X drive to the Z drive and that motor had the same issues as the Z drive. Randomly stalled and moved in random directions.

It if definitely seems the driver is the problem not the motor. I'm going to do some more investigation on how exactly the Z stage has failed. I would be EXTREMELY surprised if the problem is in the digital domain but the random movement of the motor kinda of indicates that. But the motor sometimes stalling also indicates some output stage problem. Very confusing. I'll update after I investigate more.

I went ahead and said fuck it and just completely look apart the motor since I planned on replacing it anyway so I can see if there is some obvious failure and I have never taken apart a stepper before. After looking inside if it and seeing how it's made, it looked so simple I would be astonished if this thing actually failed short if literally the inductor wire frying. I cleaned up the inside, put everything back together and the motor still seemed to worked the same.

Now I took a closer look at the Rambo board as now that is really suspect, and on closer examination it looked like the stepper motor drives for each axis is identical. I went ahead and connected the Z motor to the X and Y drive. It seemed to work perfect other than turning slower. It never stalled and it always turned in the correct direction. Connected it back to the Z driver and the problems were back. I then connected the X drive to the Z drive and that motor had the same issues as the Z drive. Randomly stalled and moved in random directions.

It if definitely seems the driver is the problem not the motor. I'm going to do some more investigation on how exactly the Z stage has failed. I would be EXTREMELY surprised if the problem is in the digital domain but the random movement of the motor kinda of indicates that. But the motor sometimes stalling also indicates some output stage problem. Very confusing. I'll update after I investigate more.

That would point to a driver issue. They are built in so you would have to swap the board. You could go for Einsy Rambo board, its cheaper and has tmc 2130 drivers which are quiter. Only issue is Einsy rambo supports 5v fans. Another option would be Einsy retro which supports 24v fans and no need to swap them.

I went ahead and said fuck it and just completely look apart the motor since I planned on replacing it anyway so I can see if there is some obvious failure and I have never taken apart a stepper before. After looking inside if it and seeing how it's made, it looked so simple I would be astonished if this thing actually failed short if literally the inductor wire frying. I cleaned up the inside, put everything back together and the motor still seemed to worked the same.

Now I took a closer look at the Rambo board as now that is really suspect, and on closer examination it looked like the stepper motor drives for each axis is identical. I went ahead and connected the Z motor to the X and Y drive. It seemed to work perfect other than turning slower. It never stalled and it always turned in the correct direction. Connected it back to the Z driver and the problems were back. I then connected the X drive to the Z drive and that motor had the same issues as the Z drive. Randomly stalled and moved in random directions.

It if definitely seems the driver is the problem not the motor. I'm going to do some more investigation on how exactly the Z stage has failed. I would be EXTREMELY surprised if the problem is in the digital domain but the random movement of the motor kinda of indicates that. But the motor sometimes stalling also indicates some output stage problem. Very confusing. I'll update after I investigate more.

That would point to a driver issue. They are built in so you would have to swap the board. You could go for Einsy Rambo board, its cheaper and has tmc 2130 drivers which are quiter. Only issue is Einsy rambo supports 5v fans. Another option would be Einsy retro which supports 24v fans and no need to swap them.

I'll probably just end up ordering another board today but I'm still curious as to what in the driver staged failed. It looks like the logic input to the stepper driver is fine (looked at the signals on the oscilloscope). Step and direction signals on the Z input look exactly like the X/Y input. I'm guessing one or more of the transistors on the output stage of the stepper IC is on the verge of failing. It would also sort-of explain the motor going in the wrong direction is the current direction at the output is the opposite of what it should be if one of the transistors fails to turn on or one of the transistors randomly shorts.

Do you (or anyone else here) happen on know exactly what IC for the stepper the Rambo uses? Or even better a full schematic of the board?

New Rambo board came today and the z axis is working properly now. The failure point was definitely the stepper motor driver. I plan to buy some heatsinks to stick onto the stepper motor drivers and replace the cooling fan and hopefully reduce the likelihood of failure in the future.